Electronic components and mounting structures for electronic components

Abstract

An electronic component 1 includes: a substrate 10, external electrodes 21 and 22 disposed on the substrate 10, and a plurality of particle-shaped metal portions 31. The external electrodes 21 and 22 have: a base electrode film 23 disposed on the substrate 10, a Ni plating film 24 disposed to cover the base electrode film 23, and a Sn plating film 26 disposed to cover the Ni plating film 24. The plurality of particle-shaped metal portions 31 exist independently of the Ni plating film 24 and are covered by the Sn plating film 26.

Description

Technical Field

[0001] This invention relates to electronic components and mounting structures for electronic components. Background Technology

[0002] Patent Document 1 Figure 1 The paper describes a multilayer ceramic capacitor, which is constructed by forming an external electrode for electrical connection with the internal electrode layers on a ceramic laminate consisting of alternating layers of dielectric ceramic layers and internal electrode layers for obtaining capacitance. This external electrode has a three-layer structure: first, an Ag electrode is formed on the surface of the ceramic laminate by sintering silver paste; then, a Ni electrode is formed on top of this as an intermediate layer; and finally, a Sn electrode is formed on top of this as the outermost layer.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2000-077253 Summary of the Invention

[0006] In electronic components with external electrodes having such a structure, shortening the electrode dimension (E) of the Ni film (e.g., thinning the Ni film) can potentially worsen solder wettability and lead to reduced migration. Conversely, extending the electrode dimension (E) of the Ni film (e.g., thickening the Ni film) increases stress and causes the Ni film to move closer to the center of the substrate. Therefore, when cracks form in the substrate near the edge of the Ni film's electrode dimension, they can easily reach the effective layer, potentially leading to a decrease in mechanical strength (properties). Furthermore, extending the electrode dimension of the Ni film can reduce properties such as capacitance.

[0007] The present invention was made to solve the above-mentioned problems, and aims to provide electronic components and mounting structures for electronic components that enable thin-film formation of Ni films for external electrodes and have excellent solder wettability and migration inhibition.

[0008] The electronic component of the present invention includes: a substrate, an external electrode disposed on the substrate, and a plurality of particle-shaped metal portions. The external electrode has: a base electrode film disposed on the substrate, a Ni plating film disposed to cover the base electrode film, and a Sn plating film disposed to cover the Ni plating film. The plurality of particle-shaped metal portions exist independently of the Ni plating film and are covered by the Sn plating film.

[0009] The mounting structure of the electronic component of the present invention includes the electronic component of the present invention and a mounting substrate. The mounting substrate includes: a substrate body having a mounting surface and a pad electrode formed on the mounting surface. The external electrode of the electronic component is electrically connected to the pad electrode by solder. The surfaces of the plurality of particle-shaped metal portions are each made of Sn alloy.

[0010] According to the present invention, it is possible to provide electronic components and mounting structures for electronic components that enable the thinning of Ni films for external electrodes and also provide excellent solder wettability and migration inhibition. Attached Figure Description

[0011] Figure 1 This is a perspective view schematically illustrating an example of an electronic component according to an embodiment of the present invention.

[0012] Figure 2 yes Figure 1 An example of a cross-sectional view along line A-A of an electronic component is shown.

[0013] Figure 3 yes Figure 1 Another example of the cross-sectional view of the electronic component shown along line A-A illustrates the case where the electronic component is a multilayer ceramic capacitor.

[0014] Figure 4 It is Figure 1 An enlarged top view of the particle-like metal portion of the electronic component shown.

[0015] Figure 5 yes Figure 4 An example of a B-B line cross-sectional view of an electronic component is shown.

[0016] Figure 6 It is shown schematically. Figure 1 The top view of the modified example of the electronic component shown is an enlarged view of the particle-shaped metal part.

[0017] Figure 7 It is shown schematically. Figure 1 The top view of another variation of the electronic component shown is an enlarged view of the particle-shaped metal portion.

[0018] Figure 8 This is a cross-sectional view schematically illustrating an example of a particle-shaped metal portion according to an embodiment of the present invention.

[0019] Figure 9 This is a cross-sectional view schematically illustrating a modified example of a particle-shaped metal portion according to an embodiment of the present invention.

[0020] Figure 10This is a cross-sectional view schematically illustrating another variation of the particle-shaped metal portion of an embodiment of the present invention.

[0021] Figure 11 This is a cross-sectional view schematically illustrating an example of how a solution is filled in a probe in a method for manufacturing an electronic component according to an embodiment of the present invention.

[0022] Figure 12 This is a cross-sectional view schematically illustrating an example of an apparatus used in a method for manufacturing an electronic component according to an embodiment of the present invention.

[0023] Figure 13 This is a cross-sectional view schematically illustrating an example of how the tip of a probe is brought close to the substrate of an electronic component in a method for manufacturing an electronic component according to an embodiment of the present invention.

[0024] Figure 14 This is a cross-sectional view schematically illustrating an example of how a meniscus is formed between a substrate and a probe in a method for manufacturing an electronic component according to an embodiment of the present invention.

[0025] Figure 15 This is a cross-sectional view schematically illustrating an example of a method for manufacturing an electronic component according to an embodiment of the present invention, in which particulate metal particles are extruded onto a substrate.

[0026] Figure 16 This is a cross-sectional view schematically illustrating an example of a method for manufacturing an electronic component according to an embodiment of the present invention, in which a probe is scanned on a substrate.

[0027] Figure 17 This is a perspective view schematically illustrating another example of a method for manufacturing an electronic component according to an embodiment of the present invention.

[0028] Figure 18 This is a perspective view schematically illustrating an example of a mounting structure for an electronic component according to an embodiment of the present invention. Detailed Implementation

[0029] The electronic components and mounting structures of the electronic components of the present invention will be described below.

[0030] However, the present invention is not limited to the following configurations and can be appropriately modified and applied without changing the spirit of the invention. It should be noted that configurations combining two or more of the preferred configurations described below are also part of the present invention.

[0031] (Electronic components)

[0032] First, the electronic components of the embodiments of the present invention will be described. Figure 1This is a perspective view schematically illustrating an example of an electronic component according to an embodiment of the present invention.

[0033] Figure 1 The electronic component 1 shown is a small chip-type electronic component (surface mount type electronic component), which includes: a substrate 10, and external electrodes 21 and 22 disposed on the substrate 10.

[0034] The size of electronic component 1 is not particularly limited. For example, it can be a size greater than 1005, 1005, 0603, 0402, 0201, etc.

[0035] The specific type of electronic component 1 is not particularly limited. Specifically, examples include laminated ceramic capacitors, laminated coils, laminated thermistors, laminated varistors, laminated LC filters, laminated piezoelectric filters, and other laminated ceramic electronic components.

[0036] In this case, the substrate 10 is preferably a laminate formed by stacking at least one of a dielectric ceramic layer, a magnetic ceramic layer, a piezoelectric ceramic layer, and a semiconductor ceramic layer with an internal electrode layer serving as an internal conductor.

[0037] Furthermore, electronic component 1 may not be a stacked component as described above. For example, silicon capacitors, ferrite coils, and inductors made of composite materials of metal powder and resin can be cited as specific examples in this case.

[0038] The substrate 10 includes a dielectric layer 11 and an internal conductor (internal electrode layer). Figure 1 (Not shown in the figure) It has: a top surface 10a and a bottom surface 10b opposite each other in the height direction T, a first side surface 10c and a second side surface 10d opposite each other in the length direction L orthogonal to the height direction T, and a third side surface 10e and a fourth side surface 10f opposite each other in the width direction W orthogonal to the height direction T and the length direction L.

[0039] Thus, the base 10 has a roughly cuboid shape, and the corners and ridges can be rounded. The corners are the parts where three faces of the base 10 intersect, and the ridges are the parts where two faces of the base 10 intersect.

[0040] The electronic component 1 is mounted on the mounting substrate with its bottom surface 10b facing the mounting surface of the mounting substrate. That is, the bottom surface 10b is the mounting surface.

[0041] It should be noted that the areas of the top surface 10a and the bottom surface 10b may or may not be substantially the same as the areas of the third side surface 10e and the fourth side surface 10f. Similarly, the areas of the first side surface 10c and the second side surface 10d may or may not be substantially the same as the areas of the third side surface 10e and the fourth side surface 10f.

[0042] Except for the exposed portion of the internal conductor, the surface of the substrate 10 is composed of a dielectric layer 11.

[0043] The dielectric layer 11 may be formed of a dielectric material (oxide), for example. The dielectric material may be appropriately selected according to the type of electronic component 1, for example, dielectric ceramic materials, magnetic ceramic materials, piezoelectric ceramic materials, semiconductor ceramic materials, etc.

[0044] Examples of dielectric ceramic materials include those containing barium titanate, calcium titanate, strontium titanate, barium calcium titanate, or calcium zirconate as main components. When the above-mentioned dielectric ceramic material is used as the main component, electronic component 1 can function as a multilayer ceramic capacitor. Materials containing less than the main component, such as Mg compounds, Mn compounds, Si compounds, Al compounds, V compounds, Ni compounds, and rare earth compounds, can be used to achieve the desired characteristics of the multilayer ceramic capacitor.

[0045] As a magnetic ceramic material, examples include magnetic ceramic materials containing ferrite ceramic materials as the main component. When using a magnetic ceramic material, electronic component 1 can function as a multilayer coil.

[0046] Specific examples of piezoelectric ceramic materials include, for instance, PZT (lead zirconate titanate) based ceramic materials. When using piezoelectric ceramic materials, electronic component 1 can function as a stacked piezoelectric filter.

[0047] Specific examples of semiconductor ceramic materials include spinel-based ceramic materials. When using semiconductor ceramic materials, electronic component 1 can function as a multilayer thermistor.

[0048] External electrodes 21 and 22 are disposed on the surface of the substrate 10.

[0049] The external electrode 21 is disposed on the first side 10c of the substrate 10. Figure 1 In this structure, external electrodes 21 are continuously disposed on the top surface 10a, bottom surface 10b, third surface 10e, and fourth surface 10f of the substrate 10, starting from the first side surface 10c. The external electrodes 21 are electrically connected to the internal conductor exposed from the substrate 10 on the first side surface 10c.

[0050] The external electrode 22 is disposed on the second side 10d of the substrate 10. Figure 1 In this structure, external electrodes 22 are continuously disposed on the top surface 10a, bottom surface 10b, third surface 10e, and fourth surface 10f of the substrate 10, starting from the second side surface 10d. The external electrodes 22 are electrically connected to the internal conductor exposed from the substrate 10 on the second side surface 10d.

[0051] It should be noted that the length direction L of the external electrodes 21 and 22 on the top surface 10a, bottom surface 10b, third side surface 10e, and fourth side surface 10f is equivalent to the E dimension of the external electrodes 21 and 22.

[0052] Figure 2 yes Figure 1 This is an example of a cross-sectional view along line A-A of an electronic component. It should be noted that... Figure 2 The diagram of the internal conductor of the substrate 10 is omitted.

[0053] like Figure 2 As shown, the external electrodes 21 and 22 have a resin electrode layer 23 disposed on the substrate 10 as a base electrode film. The resin electrode layer 23 contains a conductive component and a resin component. The conductive component includes elemental metals such as silver, copper, nickel, and tin, or alloys containing at least one of these metals as the main component. The resin component includes epoxy resin, phenolic resin, etc. as the main component. The resin electrode layer 23 can be formed using a conductive paste such as silver paste.

[0054] It should be noted that the external electrodes 21 and 22 may have a sintered copper or silver electrode layer disposed on the substrate 10 instead of the resin electrode layer 23 as the base electrode film. Specifically, the sintered copper or silver electrode layer is an electrode formed by sintering a copper or silver paste containing glass components.

[0055] Furthermore, the external electrodes 21 and 22 have a so-called coating formed by plating on the resin electrode layer 23 (or it may be a sintered electrode layer of copper or silver. The same applies below.). Specifically, they have a Ni coating 24 that is provided to cover the resin electrode layer 23 and a Sn coating 26 that is provided as the outermost layer to cover the Ni coating 24.

[0056] It should be noted that in this invention, the external electrode only needs to be disposed on a portion of the surface of the substrate, and its placement location is not particularly limited. For example, it can be disposed only on the bottom surface of the substrate, or it can cover a portion of any side of the substrate and be disposed in a manner that extends from that side to cover a portion of the bottom surface (with an L-shaped cross-section), or it can cover a portion or all of any side of the substrate and be disposed in a manner that extends from that side to cover a portion of the top surface and a portion of the bottom surface (with a U-shaped (C-shaped) cross-section).

[0057] Furthermore, the number of external electrodes is not particularly limited in this invention; at least one external electrode needs to be provided on the substrate. For example, four (4 terminals) or six (6 terminals) electrodes can be provided on the substrate.

[0058] Figure 3 yes Figure 1Another example of the cross-sectional view of the electronic component shown along line A-A illustrates the case where the electronic component is a multilayer ceramic capacitor.

[0059] In this case, the substrate 10 is a laminate formed by stacking a dielectric ceramic layer 12, which serves as a dielectric layer 11, and internal electrode layers 13 and 14, which serve as internal conductors.

[0060] The internal electrode layer 13 is led out to the first side 10c of the substrate 10 and connected to the external electrode 21, and the internal electrode layer 14 is led out to the second side 10d of the substrate 10 and connected to the external electrode 22.

[0061] The dielectric ceramic layer 12 can be obtained by molding a dielectric slurry containing dielectric ceramic material and organic solvent into a sheet.

[0062] The internal electrode layers 13 and 14 can be obtained by printing an electrode paste containing conductive components. The internal electrode layers 13 and 14 are preferably Ni electrode layers using Ni as the conductive component.

[0063] Alternatively, Ag, Pd, or Cu electrode layers can be used instead of Ni electrode layers.

[0064] Figure 4 It is Figure 1 An enlarged top view of the particle-like metal portion of the electronic component shown. Figure 5 yes Figure 4 This is an example of a B-B line cross-sectional view of an electronic component. It should be noted that... Figure 4 This shows the state revealed by a perspective view of the Sn coating 26.

[0065] like Figures 1-5 As shown, a plurality of particle-shaped metal portions 31 are further provided on the substrate 10. These particle-shaped metal portions 31 exist independently of the Ni coating 24 in an island-like manner and are covered by the Sn coating 26. By having such particle-shaped metal portions 31, even when the Ni coating 24 (i.e., the Ni film) is made thin, excellent solder wetting and migration suppression effects can be obtained. Furthermore, since the Ni coating 24 can be made thin, crack formation in the substrate 10 can be suppressed near the E-dimensional end of the Ni coating 24. In addition, properties such as electrostatic capacitance can also be improved.

[0066] Multiple particle-shaped metal portions 31 exist independently of the Ni coating 24 in an island-like manner. It should be noted that, here, "the particle-shaped metal portions exist independently of the Ni coating" means that the particle-shaped metal portions exist on the substrate in a location separate from the Ni coating.

[0067] The placement location of the particle-shaped metal portion 31 on the substrate 10 is not particularly limited as long as it is outside the placement area of ​​the Ni coating 24 and within the placement area of ​​the Sn coating 26. Since the aforementioned effect is achieved at the location where the particle-shaped metal portion 31 is present, therefore... Figure 1 and Figure 4 As shown, it is preferably arranged in a linear shape (more preferably annular shape) along the end of the Ni coating 24.

[0068] Additionally, the particle-shaped metal portion 31 may be disposed on at least one of the top surface 10a, bottom surface 10b, third side surface 10e, and fourth side surface 10f, preferably on each of the top surface 10a, bottom surface 10b, third side surface 10e, and fourth side surface 10f where the external electrodes 21 and 22 are located.

[0069] like Figure 4 As shown, the particle-shaped metal portion 31 is preferably disposed within a range d1 of 300 μm or less (more preferably within 100 μm or less, and even more preferably within 50 μm) from the E-dimensional end of the Ni coating 24. Therefore, the particle-shaped metal portion 31 can be easily formed by the manufacturing method described later. On the other hand, the particle-shaped metal portion 31 may not be disposed in a region exceeding the range d1 of 300 μm or less (more preferably within 100 μm or less, and even more preferably within 50 μm) from the E-dimensional end of the Ni coating 24.

[0070] like Figure 4 As shown, the plurality of particle-shaped metal portions 31 may contain a single (isolated) metal particle 32. That is, at least a portion of the plurality of particle-shaped metal portions 31 may also be a single metal particle 32. Here, a "single metal particle" refers to a metal particle that is not bonded (e.g., metallically bonded) to any other particle-shaped metal portion.

[0071] In this case, the maximum length of the particle-shaped metal portion 31 (the metal particle 32 existing alone) in the top view is preferably 1 nm to 2000 nm, more preferably 1 nm to 1000 nm, and even more preferably 1 nm to 500 nm.

[0072] In addition, in this case, the maximum thickness of the particulate metal portion 31 (the metal particles 32 existing alone) is preferably 1 nm to 1500 nm, more preferably 1 nm to 900 nm, and even more preferably 1 nm to 400 nm.

[0073] It should be noted that the particle-shaped metal portion 31 can be observed, for example, by a scanning electron microscope (SEM) or a microscope capable of magnification of 5000x or more, and the maximum length and maximum thickness in the aforementioned top view can also be determined based on this observed image. Here, "top view" refers to observation from a direction orthogonal to the surface of the substrate 10 (wherein, is the surface on which the metal portion is located).

[0074] Figure 6 It is shown schematically. Figure 1 The top view of the modified example of the electronic component shown is an enlarged view of the particle-like metal portion. It should be noted that... Figure 6 This shows the state revealed by a perspective view of the Sn coating 26.

[0075] Although the particle-shaped metal part 31 is based on individual metal particles (metal particles 32), it can also be like... Figure 6 The diagram shows a plurality of continuously arranged particle-shaped metal portions 33. That is, at least a portion of the plurality of particle-shaped metal portions 31 can be a plurality of continuously arranged particle-shaped metal portions 33. Furthermore, the further away from the Ni coating 24, the fewer the continuously arranged particle-shaped metal portions 33 become, while the number of individually existing metal particles 32 can increase. Here, "a plurality of continuously arranged particle-shaped metal portions" refers to a metal portion that extends in a linear fashion as a whole through bonding (e.g., metal bonding) between each particle-shaped metal portion and other adjacent particle-shaped metal portions. The continuously arranged particle-shaped metal portions 33 can be, for example, Figure 6 The state shown can be a branched state or a single, unbranched state.

[0076] In addition, such as Figure 6 As shown, the particle-shaped metal portions 31 can exist at the grain boundaries 41 of the substrate 10. Thus, the substrate 10 can be composed of multiple grains 42, and the particle-shaped metal portions 31 can also exist in their depressions (grain boundaries 41 on the surface). The ratio of the particle-shaped metal portions 31 existing within the grains of the substrate 10 (the region enclosed by the grain boundaries 41) to the particle-shaped metal portions 31 existing at the grain boundaries 41 of the substrate 10 can, for example, be in the range of 100 / 1 to 1 / 100 (intra-grain / grain boundary).

[0077] In addition, such as Figure 6 As shown, the particle-shaped metal portion 31 may include a plurality of particle-shaped metal portions 33 that are continuous in a linear manner at the grain boundaries 41 of the substrate 10 and a plurality of metal particles 32 that are sparsely or dispersedly present within the grains of the substrate 10.

[0078] Figure 7 It is shown schematically. Figure 1The top view of another variation of the electronic component shown is an enlarged view of the particle-like metal portion. It should be noted that... Figure 7 This shows the state revealed by a perspective view of the Sn coating 26.

[0079] like Figure 7 As shown, the particle-shaped metal portion 31 can become smaller with increasing distance from the Ni coating 24. More specifically, the maximum length and maximum thickness of the particle-shaped metal portion 31 in the top view can become smaller with increasing distance from the Ni coating 24. It should be noted that the metal portion 31 that becomes smaller with increasing distance from the Ni coating 24 in this case can be a single metal particle 32 (see reference). Figure 7 It can be a linear, continuous, particle-like metal part, or it can include both.

[0080] The particle-shaped metal portions 31 are preferably located within 2 μm of the nearest particle-shaped metal portion 31, more preferably within 1 μm, and even more preferably within 0.5 μm. It should be noted that the metal portions 31 located within 2 μm can be individual metal particles, linearly continuous particle-shaped metal portions, or a combination of individual metal particles and any metal portions included in linearly continuous particle-shaped metal portions.

[0081] The three-dimensional shapes of the particle-like metal portions 31 are typically spherical, oblate, hemispherical, disc-shaped with a central depression on both sides, snowman-shaped, etc. It should be noted that metal portions 31 with different three-dimensional shapes can be mixed together. In the case of a hemispherical shape, the particle-like metal portions 31 are typically disposed on the substrate 10 with their planar portions in contact with the surface of the substrate 10. Furthermore, in this case, typically, the planar portions of the metal portions 31 and the surfaces of the substrate 10 in contact with their planar portions each have fine irregularities, resulting in a state where the irregularities of the metal portions 31 and the irregularities of the substrate 10 fit together. That is, the planar portions of the metal portions 31 are in contact with the irregular surfaces of the substrate 10 without gaps, resulting in a state where the fine irregularities of the substrate 10 are transferred to the planar portions of the metal portions 31.

[0082] The shape (planar shape, shape projected onto the surface of the substrate 10) of each of the particle-like metal parts 31 in its top view is preferably circular, elliptical, polygonal, or a shape formed by the overlap of at least two of these shapes. In this case, metal parts 31 with different planar shapes can be mixed together. Examples of polygons include triangular, heptagonal, and dodecagonal shapes.

[0083] The material of the particle-shaped metal part 31 is not particularly limited except for Sn, and examples include Ni, Cu, Au, Ag, etc. Among them, Ni and Cu are preferred from the viewpoints of having a melting point above the installation temperature (e.g., 250°C) and being inexpensive.

[0084] Figure 8 This is a cross-sectional view schematically illustrating an example of a particle-shaped metal portion according to an embodiment of the present invention. Figure 9 This is a cross-sectional view schematically illustrating a modified example of a particle-shaped metal portion according to an embodiment of the present invention. Figure 10 This is a cross-sectional view schematically illustrating another variation of the particle-shaped metal portion of an embodiment of the present invention.

[0085] like Figure 8 As shown, the particle-shaped metal portion 31 may be entirely composed of metal 31a other than Sn. On the other hand, as... Figure 9 and Figure 10 As shown, the surface of the particle-like metal portion 31 can be composed of Sn alloy 31b. More specifically, as... Figure 9 As shown, the particle-shaped metal portion 31 may have a surface composed of Sn alloy 31b and an interior composed of a metal 31a other than Sn. Additionally, as... Figure 10 As shown, the particle-shaped metal portion 31 can be entirely composed of a Sn alloy 31b. Here, the Sn alloy 31b is an alloy formed by alloying the metal elements constituting the particle-shaped metal portion 31 (wherein, is a metal element other than Sn) with the Sn constituting the Sn coating 26. Examples include Ni-Sn alloy, Cu-Sn alloy, Au-Sn alloy, and Ag-Sn alloy. Such a Sn alloy can be generated at room temperature before the electronic component 1 is installed by connecting the particle-shaped metal portion 31 to the Sn coating 26. Alternatively, the Sn alloy can also be generated by performing heat treatment on the electronic component 1 after the Sn coating 26 is formed and before solder installation. The temperature and time of this heat treatment can be in the range of 120°C to 170°C for about 30 minutes to 5 hours, and sometimes preferably at 140°C to 160°C for about 1 hour.

[0086] Figure 5The illustration shows a case where particulate metal portions 31 are directly disposed on the substrate 10 and the Sn coating 26 directly covers the particulate metal portions 31. However, a glass coating film can also be formed on the substrate 10, and the particulate metal portions 31 can be disposed on the substrate 10 through the glass coating film, with the Sn coating film 26 directly covering the particulate metal portions 31 on the glass coating film. Alternatively, a glass coating film can be provided to cover the particulate metal portions 31 directly disposed on the substrate 10, and the Sn coating film 26 can also cover the particulate metal portions 31 through the glass coating film.

[0087] There is no particular limitation on the type of glass used to form the glass coating. Examples include glasses containing SiO2, TiO2, Al2O3 or mixtures thereof, various additives, fillers, etc. Among these, glasses with SiO2 as the main component are readily available, and the range of compositions containing additives is wide.

[0088] The thickness of the glass coating is not particularly limited, but is preferably 50nm to 3000nm, more preferably 300nm to 2000nm, and even more preferably 500nm to 1500nm.

[0089] (Manufacturing methods for electronic components)

[0090] Next, the manufacturing method of the electronic component 1 of the above embodiment, particularly the particle-shaped metal portion 31, will be described. The components other than the particle-shaped metal portion 31 can be manufactured using the same methods as general electronic components.

[0091] The particle-shaped metal portion 31 can be formed simultaneously with or after the formation of the Ni plating film 24 (during or after the Ni plating process) by electroplating. That is, the particle-shaped metal portion 31 can serve as a plating nucleus. Electroplating can be either barrel plating or rack plating. The particle-shaped metal portion 31 can be formed near the Ni plating film 24 by either method. More specifically, it has been confirmed that the particle-shaped metal portion is formed near the Ni plating film by fabricating an electronic component with an external electrode using the following method.

[0092] First, a Ni coating is formed using a plating solution containing nickel salts (nickel sulfate: 240 g / L, nickel chloride: 45 g / L) and a buffer (boric acid: 30 g / L) by the following method 1.

[0093] -Method 1

[0094] The 5A coating is applied using a barrel plating process for 60 minutes.

[0095] After forming a Ni coating, a Sn coating is formed using a plating solution containing Sn salt, a complexing agent, and additives, according to the following method 2.

[0096] -Method 2

[0097] The Sn layer is formed using a barrel plating process. Specifically, the object to be treated, the plating solution, and the metal used to ensure conductivity are introduced into a barrel plating apparatus, and the process is carried out at 6A for 75 minutes.

[0098] Alternatively, the particle-shaped metal portion 31 can also be formed using a probe method. This will be described in detail below.

[0099] In this case, firstly, prepare a solution containing metal ions.

[0100] Examples of metal ions include Ni ions, Cu ions, Au ions, and Ag ions. Among these, Ni ions and Cu ions are preferred from the viewpoints of having a melting point above the installation temperature (e.g., 250°C) and being inexpensive.

[0101] As solutions containing metal ions, for example, nickel sulfate bath, nickel aminosulfonate bath, copper sulfate bath, copper pyrophosphate bath, gold cyanide bath, sodium gold sulfite bath, silver cyanide bath, silver methanesulfonate bath, etc. can be used.

[0102] The concentration of metal ions in the solution is not particularly limited, but is preferably 0.1 mol / L to 2 mol / L, and more preferably 0.5 mol / L to 1.5 mol / L.

[0103] Figure 11 This is a cross-sectional view schematically illustrating an example of how a solution is filled in a probe in a method for manufacturing an electronic component according to an embodiment of the present invention. Figure 12 This is a cross-sectional view schematically illustrating an example of an apparatus used in a method for manufacturing an electronic component according to an embodiment of the present invention. It should be noted that... Figure 12 and the following Figure 13 The diagram of the internal conductor of the substrate 10 is omitted.

[0104] Next, as Figure 11 As shown, the above-mentioned solution 61 is filled into a cylindrical probe 63 in which an electrode 62 is disposed. The probe 63 is a cylindrical shape that gradually tapers towards the front end, and is fixed in place with the rod-shaped electrode 62 inserted into its internal space.

[0105] The probe 63 has a circular opening at its front end, as shown in the top view. The diameter of the front end of the probe 63 (the radius of the opening) is preferably 10 nm to 1000 nm, more preferably 100 nm to 500 nm.

[0106] like Figure 11 As shown, one end of electrode 62 is inserted near the front end of probe 63, as... Figure 12As shown, the other end is electrically connected to the power supply mechanism 64. The material of electrode 62 is not particularly limited; for example, a hydrogen electrode, silver chloride electrode, or other common reference electrode can be used. The distance d2 between one end of electrode 62 and the tip of probe 63 is preferably 1 μm to 100 μm, more preferably 10 μm to 50 μm.

[0107] Figure 12 The electronic component 1A shown corresponds to the stage after the formation of the Ni coating 24 and before the formation of the particle-shaped metal portion 31 and the Sn coating 26 (it is the same as electronic component 1 except that the particle-shaped metal portion 31 and the Sn coating 26 are not formed), and is disposed on the power supply board 65 in contact with the Ni coating 24. That is, electronic component 1A is a monolithically formed electronic component after calcination. The power supply board 65 is electrically connected to the power supply mechanism 64.

[0108] A position control device (not shown) is connected to the probe 63 to control its position in three-dimensional space. The position control device includes, for example, a Z-axis stage that movably holds the probe 63 in the Z direction (vertical direction, e.g., height direction T), an XY-axis stage that movably holds the mounted power supply plate 65 in the XY direction (horizontal direction, e.g., a direction parallel to the length direction L and width direction W), and a controller that controls the Z-axis stage and the XY-axis stage.

[0109] Figure 13 This is a cross-sectional view schematically illustrating an example of how the tip of a probe is brought close to the substrate of an electronic component in a method for manufacturing an electronic component according to an embodiment of the present invention. Figure 14 This is a cross-sectional view schematically illustrating an example of how a meniscus is formed between a substrate and a probe in a method for manufacturing an electronic component according to an embodiment of the present invention.

[0110] Next, as Figure 13 As shown, the X, Y, and Z points of probe 63 are controlled to bring the tip of probe 63 close to the substrate 10 of electronic component 1A (probe position control process). That is, the position control device is used to move probe 63 so that its tip is positioned above the area of ​​substrate 10 where the particle-shaped metal portion should be formed.

[0111] Then, as Figure 14 As shown, the solution 61 flowing from the tip of the probe 63 is brought into contact with the substrate 10. Specifically, the probe 63 is moved downwards using a position control device until the solution 61 contacts the substrate 10. Furthermore, a meniscus 66 is formed between the substrate 10 and the probe 63 (meniscus formation process). As a result, the solution 61 does not wet and diffuse indefinitely on the substrate 10; instead, it remains on the substrate 10 due to its surface tension, forming a hemispherical shape. The amount of solution 61 in contact with the substrate 10 is extremely small.

[0112] At this time, the shortest distance d3 between the tip of the probe 63 and the substrate 10 is preferably 15nm to 1500nm, more preferably 150nm to 750nm, and even more preferably 300nm to 750nm.

[0113] The radius of the meniscus 66 is not particularly limited, but is preferably 20nm to 2000nm, more preferably 50nm to 1000nm, and even more preferably 100nm to 500nm.

[0114] Figure 15 This is a cross-sectional view schematically illustrating an example of a method for manufacturing an electronic component according to an embodiment of the present invention, in which particulate metal particles are extruded onto a substrate.

[0115] Next, as Figure 15 As shown, with the meniscus 66 formed, a voltage is applied between the Ni-plated film 24 of the electronic component 1A and the electrode 62, causing particle-shaped metal portions 31 to precipitate on the substrate 10 (metal particle precipitation process). Specifically, when the Ni-plated film 24 is powered by the power supply mechanism 64, a leakage current is generated, and metal ions are reduced on the substrate 10 to precipitate particle-shaped metal portions 31. Then, the tip of the probe 63 is moved away from the meniscus 66.

[0116] A pulsed voltage is applied to the Ni-coated film 24 and the electrode 62 in the cathode direction. The particle radius of the granular metal portion 31 can be controlled by controlling this voltage. Specifically, the greater the value of the pulsed voltage and the longer the application time of the pulsed voltage, the greater the particle radius of the deposited granular metal portion 31 can be.

[0117] The pulse voltage is preferably 1V to 100V, more preferably 10V to 50V.

[0118] In addition, the application time of the pulse voltage is preferably 100μs to 10s, more preferably 500μs to 1s.

[0119] It should be noted that a predetermined voltage can also be applied to the Ni coating 24 and the electrode 62 from the stage before the solution 61 flowing out from the tip of the probe 63 comes into contact with the substrate 10. Thus, leakage current generated at the instant the solution 61 comes into contact with the substrate 10 can be detected, and a pulsed voltage can be applied in conjunction with this detection to cause the particle-like metal portion 31 to precipitate.

[0120] Furthermore, while the leakage current may be generated by conductive portions such as the Ni coating 24 and the internal electrode layers 13 and 14, utilizing the leakage current from the Ni coating 24 allows for more effective deposition of particle-shaped metal portions 31. Therefore, as described above, the particle-shaped metal portions 31 are preferably disposed near the Ni coating 24.

[0121] Figure 16 This is a cross-sectional view schematically illustrating an example of a method for manufacturing an electronic component according to an embodiment of the present invention, in which a probe is scanned on a substrate.

[0122] Then, as Figure 16 As shown, by repeatedly performing the above-described probe 63 position control process, meniscus formation process, and metal particle precipitation process, particle-shaped metal portions 31 can be precipitated while controlling the particle radius and arrangement. Furthermore, according to this method, even when there is a height difference on the substrate 10, the probe 63 can be scanned along that height difference to form particle-shaped metal portions 31.

[0123] According to the above method, the formation site of the particle-shaped metal part 31 can be controlled with high precision.

[0124] Figure 17 This is a perspective view schematically illustrating another example of a method for manufacturing an electronic component according to an embodiment of the present invention.

[0125] The above example illustrates a method of forming particle-shaped metal portions 31 for separate, individual electronic components 1A, but it is also possible to do so as follows: Figure 17 As shown, in the stage before the semi-finished electronic component block 70 is monolithically formed into an electronic component, particle-shaped metal portions 31 are formed in each electronic component region. Then, the electronic component block 70 is cut off and monolithically formed into an electronic component. In this case, the virtual electrode 71 for power transmission can be formed only on, for example, the top and bottom surfaces. The terminal 72 that is electrically connected to the power supply mechanism 64 contacts the virtual electrode 71. After the particle-shaped metal portions 31 are formed on the top and bottom surfaces, monolithization is performed. Then, regular external electrodes can also be formed including the side and bottom surfaces. Thus, the structure of the above-described electronic component 1 (wherein only the top and bottom surfaces have particle-shaped metal portions 31) can be obtained.

[0126] (Mounting structure for electronic components)

[0127] Next, the mounting structure of the electronic component according to an embodiment of the present invention will be described. Figure 18 This is a perspective view schematically illustrating an example of a mounting structure for an electronic component according to an embodiment of the present invention.

[0128] Figure 18 The mounting structure 100 for the electronic components shown includes the aforementioned electronic component 1 and mounting substrate 110.

[0129] The mounting substrate 110 includes a substrate body 111 having a mounting surface 111a, and pad electrodes 112 and 113 formed on the mounting surface 111a. The substrate body 111 is formed of a resin such as glass epoxy or a ceramic such as glass ceramic. The substrate body 111 may be formed of multiple stacked insulating layers. The mounting surface 111a is disposed on one main surface of the substrate body 111. The pad electrodes 112 and 113 are, for example, rectangular electrodes in plan view, disposed on the mounting surface 111a.

[0130] The external electrodes 21 and 22 of the electronic component 1 are electrically connected to the pad electrodes 112 and 113 respectively via solder 120. In this way, the pad electrodes 112 and 113 are provided corresponding to each external electrode 21 and 22, and the corresponding external electrode 21 or 22 and the pad electrode 112 or 113 are connected and fixed to each other via solder 120.

[0131] Solder 120 is composed of an alloy with Sn as the main component and contains flux. Solder 120 is bonded to the outermost Sn plating film 26, which serves as the outermost electrode 21, 22.

[0132] The electronic component 1 is mounted on the mounting substrate 110 such that the top surface 10a of the substrate 10 faces the side opposite to the mounting surface 111a of the substrate body 111. That is, the bottom surface 10b of the substrate 10 is opposite to the mounting surface 111a of the substrate body 111.

[0133] Furthermore, in the mounting structure 100, the metal constituting the particle-shaped metal portion 31 is alloyed with the Sn constituting the Sn coating 26 through heat treatment (reflow soldering) during the installation of the electronic component 1. At least the surface of each particle-shaped metal portion 31 (usually the entire metal portion 31) is made of Sn alloy (see reference). Figure 9 or Figure 10 Examples of such Sn alloys include Ni-Sn alloys, Cu-Sn alloys, Ni-Cu-Sn alloys, Au-Sn alloys, and Ag-Sn alloys. It should be noted that the Ni-Cu-Sn alloy can be an alloy formed by mixing Cu from solder 120 into a Ni-Sn alloy.

[0134] In addition, in the mounting structure 100, the Ni constituting the Ni coating 24 and the Sn constituting the Sn coating 26 are alloyed by heat treatment (reflow soldering) during the installation of the electronic component 1. The surface of the Ni coating 24 (usually only the surface of the Ni coating 24) is composed of Ni-Sn alloy and / or Ni-Cu-Sn alloy.

[0135] The following content is disclosed in this specification.

[0136] <1>

[0137] An electronic component includes: a substrate, external electrodes disposed on the substrate, and a plurality of particle-shaped metal portions.

[0138] The external electrode described above includes: a base electrode film disposed on the substrate, a Ni plating film disposed to cover the base electrode film, and a Sn plating film disposed to cover the Ni plating film.

[0139] The aforementioned multiple particle-shaped metal portions exist independently of the aforementioned Ni coating and are covered by the aforementioned Sn coating.

[0140] <2>

[0141] According to the electronic component described in <1>, the shape of each of the plurality of particle-shaped metal parts in the top view is circular, elliptical, or polygonal.

[0142] <3>

[0143] According to the electronic component described in <1> or <2>, the plurality of particle-shaped metal portions contain individually existing metal particles.

[0144] <4>

[0145] According to the electronic component described in <3>, the maximum length of the metal particles in the top view is 1 nm to 2000 nm.

[0146] <5>

[0147] According to the electronic component described in <3> or <4>, the maximum thickness of the aforementioned metal particles is 1 nm to 1500 nm.

[0148] <6>

[0149] The electronic component according to any one of <1> to <5>, wherein the plurality of particle-shaped metal portions comprise a plurality of particle-shaped metal portions that are continuous in a linear manner.

[0150] <7>

[0151] The electronic component according to any one of <1> to <6>, wherein the plurality of particle-shaped metal portions become smaller the farther away from the Ni coating.

[0152] <8>

[0153] The electronic component according to any one of <1> to <7>, wherein the plurality of particle-shaped metal portions are present at the grain boundaries of the substrate.

[0154] <9>

[0155] According to the electronic component described in <8>, the plurality of particle-shaped metal portions include: a plurality of particle-shaped metal portions that are linearly continuous at the grain boundaries of the substrate, and a plurality of metal particles that are sparsely present within the grains of the substrate.

[0156] <10>

[0157] The electronic component according to any one of <1> to <9>, wherein the plurality of particle-shaped metal portions are located within 2 μm of the nearest particle-shaped metal portion.

[0158] <11>

[0159] The electronic component according to any one of <1> to <10>, wherein the plurality of particle-shaped metal portions are disposed within a range of 300 μm from the Ni coating.

[0160] <12>

[0161] An electronic component mounting structure, comprising:

[0162] The electronic components described in any one of <1> to <11>, and

[0163] A mounting substrate comprising a substrate body having a mounting surface and solder pad electrodes formed on the mounting surface.

[0164] The external electrodes of the aforementioned electronic components are electrically connected to the aforementioned pad electrodes via solder.

[0165] The surfaces of the aforementioned multiple particle-shaped metal parts are each composed of Sn alloy.

[0166] Symbol Explanation

[0167] 1.1A Electronic Components

[0168] 10 Matrix

[0169] 10a Top surface

[0170] 10b bottom surface

[0171] 10c First side

[0172] 10d Second Side View

[0173] 10e Third side

[0174] 10f Fourth side

[0175] 11 Dielectric layer

[0176] 12 Dielectric ceramic layer

[0177] 13, 14 Internal electrode layers

[0178] 21, 22 External electrodes

[0179] 23 Resin electrode layer (substrate electrode film)

[0180] 24Ni coating

[0181] 26 Sn coating

[0182] 31. Particle-like metallic parts

[0183] Metals other than 31a Sn

[0184] 31b Sn alloy

[0185] 32 metal particles

[0186] 33. A series of continuous, particle-like metallic parts.

[0187] 41 Grain boundary

[0188] 42 grains

[0189] 61 solution

[0190] 62 electrodes

[0191] 63 probes

[0192] 64 Power Supply Organization

[0193] 65 Power Supply Board

[0194] 66 Crescent Moon

[0195] 70 Electronic Component Blocks

[0196] 71 Virtual Electrode

[0197] 72 terminals

[0198] 100. Mounting structure for electronic components

[0199] 110 Mounting substrate

[0200] 111 substrate main body

[0201] 111a Mounting Surface

[0202] 112, 113 pad electrodes

[0203] 120 solder

Claims

1. An electronic component comprising: a substrate, an external electrode provided on the substrate, and a plurality of metal portions in a particle shape, the external electrode having: a base electrode film provided on the substrate, a Ni plating film provided so as to cover the base electrode film, and a Sn plating film provided so as to cover the Ni plating film, the plurality of metal portions in a particle shape being present independently of the Ni plating film and being covered by the Sn plating film.

2. The electronic component according to claim 1, wherein, a shape in a plan view of each of the plurality of metal portions in a particle shape is a circular shape, an elliptical shape, or a polygonal shape.

3. The electronic component according to claim 1 or 2, wherein the plurality of metal portions in a particle shape contain metal particles present independently.

4. The electronic component according to claim 3, wherein, a maximum length in a plan view of the metal particles is 1 nm to 2000 nm.

5. The electronic component according to claim 3 or 4, wherein a maximum thickness of the metal particles is 1 nm to 1500 nm.

6. The electronic component according to any one of claims 1 to 5, wherein the plurality of metal portions in a particle shape include a plurality of metal portions in a particle shape that are continuous in a line shape.

7. The electronic component according to any one of claims 1 to 6, wherein the plurality of metal portions in a particle shape are smaller the farther they are from the Ni plating film.

8. The electronic component according to any one of claims 1 to 7, wherein the plurality of metal portions in a particle shape are present at grain boundaries of the substrate.

9. The electronic component of claim 8, wherein, the plurality of metal portions in a particle shape include: a plurality of metal portions in a particle shape that are continuous in a line shape at grain boundaries of the substrate, and a plurality of metal particles that are present sparsely within grains of the substrate.

10. The electronic component according to any one of claims 1 to 9, wherein the plurality of metal portions in a particle shape are each located within 2 μm from a nearest metal portion in a particle shape.

11. The electronic component according to any one of claims 1 to 10, wherein the plurality of metal portions in a particle shape are disposed in a range within 300 μm from the Ni plating film.

12. The electronic component according to any one of claims 1 to 11, wherein the plurality of metal portions in a particle shape are disposed in a line along an end portion of the Ni plating film.

13. A mounting structure of an electronic component comprising: the electronic component according to any one of claims 1 to 12, and a mounting substrate having a substrate main body having a mounting surface and a pad electrode formed on the mounting surface, the external electrode of the electronic component is electrically connected to the pad electrode via solder, a surface of each of the plurality of metal portions in a particle shape is composed of a Sn alloy.

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